Optical coupling component for use in an optical communication connector and an optical connector using such optical coupling component

ABSTRACT

An optical coupling component for use in an optical communication connector is provided which comprises a pair of columnar sending side and receiving side optical functional sections and a joint section integrally molded with the optical functional sections and made from the same material as the material of the optically functional sections and having joint regions adjoining the side walls of the optical functional sections, the joint regions of the joint section having a circumferential length along the side walls of the optically functional sections which is equal to or less than a half circumference of the optically functional sections.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an optical coupling component for opticallycoupling a light-emitting element and a light-receiving element on onehand and optical fibers on the other hand for two-way opticalcommunication connector, which is designed in a quest to enhance theefficiency in transmission of optical power as well as to reducecross-talk, and an optical connector using such optical couplingcomponent.

2. Prior Art

An optical plug holding optical fibers, and an optical connector havingan optical coupling component for use in two-way optical communicationand a light-emitting element and a light-receiving element mountedtherein are coupled together to form a two-way optical communicationconnector assembly.

Prior art references include Japanese Patent Application Laid Open No.2000-304980 (issued on Nov. 2, 2000, referred to as literature 1hereinafter) and Japanese Patent Application Laid Open No. 2001-13665(issued on May 18, 2001, referred to as literature 2 hereinafter) whichdisclose integrated-type optical coupling components for use in two-wayoptical communications comprise a sending side optically functionalsection and a receiving side optically functional section integrallyconnected together by means of a joint section, and optical connectorsutilizing such components.

However, the optical coupling components disclosed in the literatures 1and 2 are ones integrally molded by using a two color molding technique,which comprise a pair of optically functional sections, and a pair oftubular protective sleeves and a joint section which sleeves and a jointsection are made from a material different from the material of whichthe optically functional sections are made, this leads to an increasedcost of manufacture.

Further, there is an unpublished earlier technique which has beendeveloped in a facility of the assignee company of the presentapplication and which concerns to a discrete-type optical couplingcomponent, an integrated-type optical coupling component, and opticalconnectors utilizing such components which are disclosed in JapanesePatent Application No. 2004-260882 (filed on Sep. 8, 2004, referred toas unpublished literature 3 hereinafter) and corresponding U.S.application and other foreign applications.

The yet publicly unknown earlier technique disclosed in the aforesaidunpublished literature 3 relating to the integrated-type opticalcoupling component for use in two-way optical communication will now bebriefly described with reference to FIGS. 12 and 13.

In FIGS. 12 and 13, the reference numeral 107 denotes an opticalcoupling component for use in a two-way optical communication connectorwhich is called sleeve unit in this unpublished literature 3.Accordingly, the term “sleeve unit” will be used in the followingexplanation:

As illustrated in FIGS. 13A-13E, the sleeve unit 107 comprises acolumnar sending side optically functional section 181, a receiving sideoptically functional section 182, a sending side sleeve 173 forpositioning and protecting the sending side optically functional section181, a receiving side sleeve 174 for positioning and protecting thereceiving side optically functional section 182, a joint section 170interconnecting the sending side and receiving side optically functionalsections 181 and 182 together, a sending side flange 171 surrounding theend portion 181 a of the sending side optically functional section 181on the light-emitting element side, and a receiving side flange 172surrounding the end portion 182 a of the receiving side opticallyfunctional section 182 on the light-receiving element side. These jointsection 170, optically functional sections 181, 182, sleeves 173, 174and flanges 171, 172 are integrally molded and made from an opticallytransparent (light-transmissive) synthetic resin such as acrylicmaterial or the like, for example.

An optical coupling component 101 utilizing the sleeve unit 107 will bedescribed with reference to FIGS. 12 to 14.

In FIG. 12, the reference numeral 110 denotes a receptacle whichcomprises a side wall 102 and a bottom wall 103. In an optical plugreceiving recess 102 a defined by the side wall 102 of the receptacle110, a cylindrical sending side optical fiber accommodating tube 111 anda cylindrical receiving side optical fiber accommodating tube 112 extendin parallel to the side wall 102 and integrally upwardly from andperpendicularly to the bottom wall 103. The bottom wall 103 has a pairof apertures 113 a and 113 b formed therethrough communicating with thesending side optical fiber accommodating tube 111 and receiving sideoptical fiber accommodating tube 112, respectively and is further formedwith an optical coupling component accommodating recess 113 in theoutside surface (under surface of the bottom wall 103 as viewed in FIG.12A).

The reference numeral 104 denotes a shield cover which is divided(vertically as viewed in FIG. 12A) by a partition 140 into two portions,a lower element accommodating portion 141 for housing an element holder105 and an upper receptacle accommodating portion 142 for housing thereceptacle 110. The partition 140 is formed in its central portion withopenings 140 a and 140 b. Suitably mounted in the element holder 105 area light-emitting element 161 and a light-receiving element 162.

The sending side optical fiber 131 is inserted into the optical plugreceiving recess 102 a of the receptacle 110 from the top side as viewedin FIG. 12A and fitted and held in place in the sending side opticalfiber accommodating tube 111 by means of a sending side fiber ferrule121. Likewise, the receiving side optical fiber 132 is fitted into thereceiving side optical fiber accommodating tube 112 from the top sideand held therein in place by means of a receiving side fiber ferrule122.

The sleeve unit 107 is inserted upwardly from outside of the bottom wall103 (from the underside of the bottom wall 103 as viewed in FIG. 12A)such that the sending side sleeve 173 is passed through the aperture 113a and fitted and positioned in the sending side optical fiberaccommodating tube 111 while the receiving side sleeve 174 is likewisepassed through the aperture 113 b and fitted and positioned in thereceiving side optical fiber accommodating tube 112 until the jointsection 170 is received in the recess 113, as shown in FIG. 12B. At thisposition, it is seen that the sending side flange 171 and the receivingside flange 172 extend beyond the surface (undersurface as viewed inFIG. 12B) of the bottom wall 103.

As is seen from FIG. 14 illustrating the sleeve unit 107 fitted in thereceptacle 110 as viewed from the sleeve unit side, the recess 113 is soshaped as to be generally complementary with the outer contour of thesleeve unit 107 (defined by the flanges 171, 172 and the joint section170). The recess 113 is formed on its inner wall surface with ridges 114(three in this example) of a semi-spherical shape in cross-sectionextending in the direction of the depth of the recess 113.

The sleeve unit 107 is press-fitted and held in place in the recess 113such that these three ridges 114 are compressed against the wall of therecess. It is also to be noted that the sleeve unit 107 has a contouredprojection 170 a whereby the sleeve unit 107 is positioned in placewithin the recess 113.

Then, the receptacle 110 with the sending side optical fiber 131 and thereceiving side optical fiber 132 incorporated therein is accommodated inthe upper receptacle accommodating portion 142 of the shield cover 104such that the sending side flange 171 and the receiving side flange 172are inserted through the openings 140 a, 140 b of the partition 140 intothe element accommodating portion 141 housing the light-emitting element161 and the light-receiving element 162 with the end portions 181 a and182 a of the optically functional sections 181 and 182 opposing thelight-emitting element 161 and the light-receiving element 162,respectively.

It should be noted here that a sending side optical signal emitted fromthe light-emitting element 161 enters the end portion 181 a of thesending side optically functional section 181 on the light-emittingelement side. The end portion 181 a of the sending side opticallyfunctional section 181 is provided at its end face (lower end as viewedin FIG. 13C) with a collimating lens 181 b. Thus, the incident sendingside optical signal passes through the collimating lens 181 b andpropagates through the sending side optically functional section 181,goes out of the section through a collimating lens 181 d formed on theend face (the upper end as viewed in FIG. 13C) of the end portion 181 cof the optically functional section 180 on the optical fiber side, andconverges onto and enters the core end face of the sending side opticalfiber 131. Thereafter, the sending side optical signal passes throughthe sending side optical fiber 131 and is sent out to the outside.

Reversely, a receiving side optical signal incoming through thereceiving side optical fiber 132 from the outside will enter thereceiving side optically functional section 182 through a collimatinglens 182 d formed on the end face (the upper end as viewed in FIG. 13C)of the end portion 182 c of the receiving side optically functionalsection 182 and then enters and is received by the light-receivingelement 162 through a collimating lens 182 b formed on the end face (thelower end as viewed in FIG. 13C) of the end portion 182 a of theoptically functional section adjacent the light-receiving element.

With the sleeve unit 107 described above, a sending side optical signalemitted from the light-emitting element 161 enters the sending sideoptically functional section 181 and is sent out to the outside via thesending side optical fiber 131 while at the same time some of thesending side optical signal readily enters the joint section 170 formedof the same optically transparent (light-transmissive) material as theoptically functional sections, so that the signal may leak out from thejoint section to the outside, undesirably leading to a transmission lossof the light. The receiving side optical signal incoming through thereceiving side optical fiber 132 from the outside and entering thereceiving side optically functional section 182 is also involved with asimilar leak problem.

In addition, with the sleeve unit 107 described above, it is to beappreciated that since the sending side optically functional section 181and the receiving side optically functional section 182 are connectedtogether by means of the joint section 170, a portion of the sendingside optical signal emitted from the light-emitting element 161 willleak into the joint section 170 and is reflected at the upper and lowerinterfaces between the joint section and the outside air whereby it mayleak into the local light-receiving element 162 via a cross-talk path asindicated by an arrow in FIG. 12B, causing a detrimental cross-talkproblem.

SUMMARY OF THE INVENTION

Subjects to be Solved by the Invention

It is an object of this invention to provide an optical couplingcomponent for use in a two-way optical communication connector which isdesigned to enhance the efficiency in transmission of optical power aswell as to reduce cross-talk and an optical connector utilizing suchcomponent.

Means by which to Solve the Subjects

In order to accomplish the object, in an attempt to provide an opticalcoupling component comprising a pair of optically functional sectionsfor a two-way optical communication and a joint section integrallyformed with the optically functional sections, the present inventioncontemplates to construct the optical coupling component in such amanner that a component part or component parts other than the opticallyfunctional sections (such as joint sections, positioning members,protecting members, or others), that is, those parts which performfunctions other than an optical waveguide and which are to be contactedwith the optically functional sections, should be joined with theoptically functional sections at surface areas as small as possible.

Specifically, according to this invention, a joint section is made fromthe same material as a columnar sending side optically functionalsection and a columnar receiving side optically functional section andintegrally molded with the optically functional sections in a mannersuch that the joint section has at opposite ends thereof joint regionswhich are joined with the optically functional sections. Each of thosejoint regions of the joint section adjoining the side walls of theoptically functional sections has to have a circumferential length whichis determined to be equal to or less than a half circumference of thecorresponding columnar optically functional sections.

In one embodiment, an optical coupling component is defined, whichcomprises a columnar sending side optical functional section and acolumnar receiving side optical functional section in a pair, both madefrom optically transparent synthetic resin material, and a joint sectionintegrally molded with said optically functional sections and made fromthe same material as the material from which said optically functionalsections are made so that said pair of said optically functionalsections are mechanically joined to each other into one piece by meansof said joint section, wherein said joint section has a body portion andopposite joint end portions, and each of the joint end portions has ajoint region adjoining a circumferential surface of the correspondingcolumnar optically functional section, the area of said joint regionbeing dimensioned so as to have a circumferential length along acircumferential direction of the corresponding columnar opticallyfunctional section equal to or less than a half circumference of thecolumnar optically functional section.

In another embodiment, the optical coupling component is furtherdefined, wherein said joint regions of said joint end portions of saidjoint section has a vertical width H that is defined to be less than thevertical width M of said joint section.

In another embodiment, the optical coupling component is furtherdefined, wherein said body portion of said joint section has a generallyV-shaped notch in a central portion thereof with an apex lower than alevel defined by a straight line extending between the lower sides ofsaid two optically functional sections.

In another embodiment, the optical coupling component is furtherdefined, wherein said body portion of said joint section has generallyU-shaped notches in a central portion thereof cut in from the top andbottom edges thereof so that said joint section can be fitted and fixedby the central portion thereof in a receptacle.

In another embodiment, an optical connector is defined, which comprisesa light-emitting element and a light-receiving element; the opticalcoupling component as described above; and a connector body for housingtherein said light-emitting and light-receiving elements and saidoptical coupling component: wherein said columnar sending side andreceiving side optically functional sections of said optical couplingcomponent are adapted to establish optical coupling between said lightemitting element and said light receiving element on one hand and asending side optical fiber and a receiving side optical fiber attachedto an optical plug on the other hand, respectively.

Effects of the Invention

The optical coupling component for use in a two-way opticalcommunication connector according to this invention is anintegrated-type optical coupling component comprising a columnar sendingside optically functional section, a columnar receiving side opticallyfunctional section, and a joint section molded integrally with theoptically functional sections and made from the same material as thematerial from which the optically functional sections are made so as tojoin the two optically functional sections together into one piece. Withthis construction, it is to be appreciated that the surface areas ofthose joint regions of the joint section adjoining the side walls of thecolumnar optically functional sections are reduced as compared with thatof the optical coupling component obtained from the unpublished earliertechnique, whereby the amount of loss of light which may leak throughthe joint section is suppressed to thereby enhance the opticaltransmission efficiency. This means that since the optical couplingcomponent for a two-way optical communication connector according to thepresent invention has a joint section integrated at opposite endsthereof with the sending side and receiving side optically functionalsections, the amount of the transmitted light which may penetrate thejoint section from the sending side optically functional section isreduced, whereby it also leads to a reduction in cross-talk.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is illustrations illustrating a first embodiment of the opticalcoupling component according to the present invention; FIG. 1A being aplan view; FIG. 1B being a front view; FIG. 1C being a perspective view;FIG. 1D being a perspective view of the respective elements separated;and FIG. 1E being a side view;

FIG. 2 is illustrations illustrating a modified form of the firstembodiment shown in FIG. 1; FIG. 2A being a plan view; FIG. 2B being afront view; FIG. 2C being a perspective view; and FIG. 2D being a sideview;

FIG. 3 is a diagram illustrating a second embodiment of the opticalcoupling component according to the present invention;

FIG. 4 is illustrations illustrating a modified form of the secondembodiment shown in FIG. 3; FIG. 4A being a plan view; FIG. 4B being afront view; FIG. 4C being a perspective view; and FIG. 4D being a sideview;

FIG. 5 is a diagram illustrating another modified form of the secondembodiment shown in FIG. 3:

FIG. 6 is illustrations illustrating the third embodiment of the opticalcoupling component according to the present invention; FIG. 6A being aplan view; FIG. 6B being a front view; FIG. 6C being a perspective view;and FIG. 6D being a side view;

FIG. 7 is illustrations illustrating a modified form of the thirdembodiment shown in FIG. 6; FIG. 7A being a plan view; FIG. 7B being afront view; FIG. 7C being a perspective view; and FIG. 7D being a sideview;

FIG. 8 is diagrams illustrating the optical coupling component beingassembled into a receptacle as shown in a circle in FIG. 1B; FIG. 8Ashowing an example of an optical connector in which the optical couplingcomponent according to the first embodiment is used; and FIG. 8B showinganother example of an optical connector in which a modified form of theoptical coupling component shown in FIG. 8A is used;

FIG. 9 is illustrations illustrating a fourth embodiment of the opticalcoupling component according to the present invention; FIG. 9A being aplan view; and FIG. 9B being a front view;

FIG. 10 is diagrams illustrating the manner in which an opticalconnector is assembled using the integrated-type optical couplingcomponent according to the first embodiment shown in FIG. 1; FIG. 10Ashowing the parts of the connector in a state before assembly; and FIG.10B showing the connector in a state after assembled;

FIG. 11 is diagrams illustrating a receptacle adapted to fit therein theintegrated-type optical coupling component according to the firstembodiment shown in FIG. 1; FIG. 11A being a front view of thereceptacle having the optical coupling component fitted therein asviewed from the optical fiber side; FIG. 11B being a front view asviewed from the receptacle side where the optical coupling component isinserted; FIG. 11C being a perspective view; and FIG. 11D being a sideview;

FIG. 12 is illustrations illustrating an yet unpublished earliertechnique; FIG. 12A showing an optical connector in a state before it isassembled using the integrated-type optical coupling component for atwo-way optical communication obtained by the earlier technique; andFIG. 12B showing the connector after assembled;

FIG. 13 is a diagram illustrating an example of the integrated-typeoptical coupling component according to the yet unpublished earliertechnique shown in FIG. 12; FIG. 13A being a plan view of the opticalcoupling component; FIG. 13B being a front view; FIG. 13C being a partlycross-sectional view taken along the one-dotted chain line in FIG. 13B;FIG. 13D being a side view; and FIG. 13E being a perspective view; and

FIG. 14 is an illustration showing the integrated-type optical couplingcomponent according to the yet unpublished earlier technique shown inFIGS. 12 and 13 being assembled into the receptacle.

BEST MODES FOR CARRYING OUT THE INVENTION

The best modes for carrying out the present invention will be describedwith reference to the first embodiment shown in FIG. 1. FIG. 1B is afront view of the optical coupling component having a joint section andoptically functional sections; FIG. 1A is a plan view of the opticalcoupling component as viewed from the top; FIG. 1E is a side view of thecomponent as viewed from the side thereof; and FIGS. 1C and 1D are aperspective view of the component.

In FIG. 1, the reference numeral 9 denotes the optical couplingcomponent for use in a two-way optical communication connector. Theoptical coupling component 9 comprises a columnar sending side opticallyfunctional section 81 and a columnar receiving side optically functionalsection 82, both made of optically transparent (light-transmissive)synthetic resin, and a joint section 90 for mechanically connecting thetwo optically functional sections into one piece. It should beunderstood here that although the joint section is intended tomechanically connect the two optically functional sections together, itwill actually act to connect the two optically functional sectionsoptically as well, because it is molded integrally with the opticallyfunctional sections and made from the same material as the opticallyfunctional sections, which results in lowering the optical transmissionefficiency, as already explained.

A sending side optical signal emitted from a light-emitting element (notshown) will enter the sending side optically functional section 81 viaits one end portion (81 a on the light-emitting element side), propagatethrough the section and emerge therefrom through the other end portion(81 c on the fiber side), followed by passing through a sending sideoptical fiber (not shown) and being delivered out to the outside. On theother hand, a receiving side optical signal incoming through a receivingside optical fiber (not shown) from the outside will enter the receivingside optically functional section 82 via its one end portion (82 c onthe fiber side), emerge therefrom through the other end portion (82 a onthe light-receiving element side), and will enter and be received by alight-receiving element (not shown).

The joint section 90 comprises a body portion 90′ and opposite joint endportions 91 and 91′ with joint regions 91 a and 91 a′ which areintegrally formed with the right or left side wall of the sending sideoptically functional section 81 and receiving side optically functionalsection 82, and further includes mounting portions 92, 92′ adapted to bepress-fitted into a receptacle as will be described hereinbelow, and anotch or cut-out 93 of V-shaped cut deeply in the body portion 90′. Itis here to be noted that the joint section 90 has a thickness E as shownin FIGS. 1C and 1E, and the joint end portions 91, 91′ have a “verticalwidth H” which is less than the vertical width M of the body portion 90′of the joint section 90 and which is designed to be less than thediameter of the columnar optically functional sections 81 and 82.Assuming that the direction of extension of the central axes of thesending side and receiving side optically functional sections 81, 82 beX-axis, that the direction perpendicular to those central axes in aplane containing the axes be Y-axis, and that the directionperpendicular to the X-axis and Y-axis be Z-axis, the aforesaidthickness E of the joint section refers to the length in the directionof X-axis while the ‘vertical width H’ refers to the length in thedirection of Z-axis (see FIGS. 1B and 1C).

What is important in the present invention is that the joint endportions 91, 91′ of the joint section 90 have joint regions 91 a and 91a′ adjoining the side walls of the columnar optically functionalsections 81, 82 (it is assumed that the joint end portions have jointregions although actually they are formed integrally with the opticallyfunctional sections) and that the length (the arcuate length from thepoint A to the point B in FIGS. 1B, 1C and 1D) of the joint regions ofthe joint section circumferential of the side walls of the columnaroptically functional sections is designed to be equal to or less than ahalf circumference of the columnar optically functional section on theside wall thereof.

Additionally, the depth D (see FIG. 1B) of the notch 93 in the cut-indirection from the top end line K of the joint section 90 is such thatthe bottom (apex) of the notch 93 is below the level of a straight lineL extending between the lowest points of the sending side and receivingside optically functional sections 81 and 82 (see FIG. 1E).

As noted above, in the optical coupling component according to thepresent invention, the joint end portions 91, 91′ of the joint section90 are designed to contact the side walls of the columnar sending sideand receiving side optically functional sections 81, 82 around thecircumferential length equal to or less than a half circumference oftheir columnar cross-sections. As opposed to this, in the opticalcoupling component of the unpublished earlier technique describedhereinbefore, the joint section is constructed so as to join the sidewalls of the columnar optically functional sections around their entirecircumferences. Comparison between the two shows that in the presentinvention the areas of the joint regions of the joint section 90 whereit adjoins the side walls of the sending side and receiving sideoptically functional sections 81, 82 are much more significantly reducedin compare to that of the unpublished earlier technique and the amountof light which would otherwise leak through the joint section is muchmore suppressed to a greater degree, whereby the optical transmissionefficiency may be further enhanced. In addition, the depth of the notch93 from the top of the joint section 90 is such that that the bottom ofthe notch 93 is below the level defined by a straight line extendingbetween the lowest points of the sending side and receiving sideoptically functional sections 81 and 82, whereby the path of leakagethat any light which may have leaked from the sending side opticallyfunctional sections 81 into the joint section 90 will take before itreaches the receiving side optically functional section 82 is extended,so that the leaked light will be attenuated during the process ofpropagating through the joint section 90 while diffusing, resulting in areduction in cross-talk.

An example of the two-way optical communication connector constructed bythe use of the optical coupling component according to the firstembodiment described above will now be described with reference to FIGS.8A, 10 and 11.

FIG. 8A is a front view of the face 3 of the receptacle 10 (the sidefrom which the optical coupling component is inserted into thereceptacle) opposing the optical elements, illustrating the opticalcoupling component 9 according to the first embodiment assembled intothe receptacle.

This drawing corresponds to that of FIG. 14 used to illustrate theunpublished earlier technique. Such receptacle 10 having the opticalcoupling component 9 fitted therein is assembled with a shield cover 4(not shown, but the one corresponding to the cover 104 shown in FIG. 12)to complete a connector 1.

FIG. 10 is cross-sectional diagrams illustrating the manner in which thetwo-way optical communication connector 1 according to the presentinvention is assembled (for the cross-sectional face refer to FIG. 8A).

FIG. 11 is diagrams illustrating a receptacle 10 for the two-way opticalcommunication connector 1 according to the present invention.

The optical connector 1 according to the present invention comprises areceptacle 10 and a shield cover 4 fitted over the receptacle. Thereceptacle 10 comprises a side wall 2 and a bottom wall 3. In an opticalplug receiving recess 2 a defined by the side wall 2 of the receptacle10, a cylindrical sending side optical fiber accommodating tube 11 and acylindrical receiving side optical fiber accommodating tube 12 extend inparallel to the side wall and integrally upwardly from andperpendicularly to the bottom wall 3 (see FIGS. 10A and 11A). The bottomwall 3 refers to a wall which corresponds to the bottom of the recess 2a as viewed inlet opening of the recess 2 a.

The bottom wall 3 has a pair of apertures 13 a and 13 b formedtherethrough communicating with the sending side optical fiberaccommodating tube 11 and receiving side optical fiber accommodatingtube 12, respectively and is further formed with an optical couplingcomponent accommodating recess 13 in the outside surface (under surfaceof the bottom wall 3 as viewed in FIG. 10A) (see FIGS. 8A and 10A).

The shield cover 4 is divided (vertically as viewed in FIG. 10A) by apartition 40 into two portions, a lower optical element accommodatingportion 41 for housing an optical element holder 5 and an upperreceptacle accommodating portion 42 for housing the receptacle 10. Thepartition 40 is formed in its central portion with openings 40 a, 40 b.Suitably mounted in the element accommodating portion 41 of the elementholder 5 are a light-emitting element 61 and a light-receiving element62.

A sending side optical fiber 31 is inserted into the optical plugreceiving recess 2 a of the receptacle 10 from the top side as viewed inFIG. 10 and fitted and held in place in the fiber receiving bore 11 a ofthe sending side optical fiber accommodating tube 11 by means of asending side fiber ferrule 21. Likewise, a receiving side optical fiber32 is fitted into the fiber receiving bore 12 a of the receiving sideoptical fiber accommodating tube 12 from the top side and held thereinin place by means of a receiving side fiber ferrule 22.

The apertures 13 a, 13 b extending through the bottom wall 3 of thereceptacle 10 in the present invention have a diameter large enough toreceive the optically functional sections 81, 82 of the optical couplingcomponent 9 and are in communication at their upper ends with the fiberreceiving bores 11 a, 11 b, respectively.

The fiber side end portion 81 c of the sending side optically functionalsection 81 of the optical coupling component 9 shown in FIG. 1 isinserted upwardly from outside of the bottom wall 3 (from the undersideof the bottom wall 3 as viewed in FIG. 10A) into the aperture 13 a suchthat the tip end 81 d is positioned so as to oppose the sending sideoptical fiber 31 fitted in the sending side optical fiber accommodatingtube 11 (see FIG. 10B) while the fiber side end portion 82 c of thereceiving side optically functional section 82 is likewise insertedupwardly from outside of the bottom wall 3 into the aperture 13 b suchthat the tip end 82 d is positioned so as to oppose the receiving sideoptical fiber 32 fitted in the receiving side optical fiberaccommodating tube 12 until the joint section 90 of the optical couplingcomponent 9 is received in the recess 13, as shown in FIGS. 8A and 10B.

The bottom wall 3 of the receptacle 10 has projections 3 a, 3 bextending outwardly (downwardly as viewed in FIG. 10A) from its outersurface. The projections 3 a, 3 b are shaped so as to surround thecylindrical perimeters of the end portion 81 a of the opticallyfunctional section 81 on the light-emitting element side and the endportion 82 a of the optically functional section 82 on thelight-receiving element side, respectively around their halfcircumferences (see FIGS. 8A, 10B and 11C).

Upon the receptacle 10 being fitted in the shield cover 4, thelight-emitting element side end portion 81 a of the optically functionalsection 81 and the light-receiving element side end portion 82 a of theoptically functional section 82 surrounded by the projections 3 a, 3 b,respectively are inserted in the openings 40 a, 40 b of the shield cover4 so that the tip ends 81 b and 82 b of the optically functionalsections are positioned to oppose the light-emitting element 61 and thelight-receiving element 62, respectively.

As is seen from FIG. 8A illustrating the optical coupling component 9fitted in the receptacle 10, the recess 13 is so shaped as to begenerally complementary with the outer contour of the optical couplingcomponent 9. The recess 13 is formed on its inner wall surface(indicated in bold lines in FIG. 8A) with ridges 14 (six in thisexample) of a semi-spherical shape in cross-section extending in thedirection of the depth of the recess 13 (direction perpendicular to theplane of the drawing in FIG. 8A).

The optical coupling component 9 is press-fitted and held in place inthe recess 13 such that these six ridges 14 are compressed against thewall of the recess. It is also to be noted that the optical couplingcomponent 9 is positioned in place within the recess 13 by means of thebody portion 90′ of the joint section.

It should be noted here that a sending side optical signal emitted fromthe light-emitting element 61 enters the light-emitting element side endportion 81 a of the sending side optically functional section 81. Theend portion 81 a of the sending side optically functional section 81 isprovided at its tip end with a collimating lens 81 b Thus, the incidentsending side optical signal is converged by the collimating lens 81 bpropagates through the sending side optically functional section 81, andis converged by a collimating lens 81 d formed on the tip of the fiberside end portion 81 c of the sending side optically functional section81 before going out of the section and enters the core end face of thesending side optical fiber 31. Thereafter, the sending side opticalsignal passes through the sending side optical fiber 31 and is sent outto the outside.

Reversely, a receiving side optical signal incoming through thereceiving side optical fiber 32 from the outside is converged by acollimating lens 82 d formed on the tip of the fiber side end portion 82c of the receiving side optically functional section 81 before enteringthe receiving side optically functional section 82, and then enters andis received by the light-receiving element 162 after being converged bya collimating lens 82 b formed on the tip of the end portion 82 a of theoptically functional section adjacent the light-receiving element.

The optical coupling component 9 according to the first embodiment isconfigured such that the surface areas of the joint regions of the jointend portions 91, 91′ of the joint section 90 needed to form the pair ofoptically functional sections in an integral form where the joint endportions adjoin the side walls of the optically functional sections arereduced as compared with those of the earlier technique, whereby theamount of light which may leak through the joint section is suppressedto thereby enhance the optical transmission efficiency. Consequently, itis to be appreciated that an optical connector utilizing such opticalcoupling component may also enhance the optical transmission efficiency.

The cross-sectional areas (M×E) of the joint end portions 91, 91′between the optical coupling component 9 and the optically functionalsections 81, 82 should be minimized so as to increase the opticaltransmission efficiency but it is restricted to be of a certain minimumsize required to insure that the molten synthetic resin flows aroundwithin a mold, depending on the type of molding synthetic resin materialused.

This minimum size in the surface area may be determined by cut-and-trymethods. Specifically, the smaller the cross-sectional areas of thejoint end portions are made, the more the optical transmissionefficiency may be enhanced. Conversely, however, the risk of causing afailure in the flow of resin during the injection molding of the resinmay be commensurately increased. In order to improve the resin flow, ithas been found that it is of use to configure the joint end portion 91or 91′ such that it has progressively increasing cross-sectional areasfrom the joint region toward the body portion thereof while the areas ofthe joint region 91 a, 91 a′ remain unchanged, as illustrated in FIG.8B. However, it is hard to determine during the design phase which ofconfigurations varying from the configuration of FIG. 8A to that of FIG.8B is the best, it is preferable that after molding prototypes of theoptical coupling component, the cross-sectional area and shape of thejoint end portions 91, 91′ be determined by modifying by chipping themold while inspecting the performances of the molded prototypes.

Accordingly, the recess 13 formed in the receptacle should be formed soas to provide a space large enough to accommodate even the configurationshown in FIG. 8B in which the vertical width H of the joint end portionsis maximized. By doing so, should the flow of molten resin materialencounter a stagnation while molding an optical coupling component usingthe mold shown in FIG. 8A, countermeasures for flow stagnation may betaken by gradually chipping the parts of the mold for the joint endportions to enlarge the cross-sectional areas of the joint end portionssufficiently to provide a normal flow.

A modified form of the first embodiment shown in FIG. 1 will bedescribed with reference to FIG. 2. This modified form is fundamentallysimilar to the embodiment of FIG. 1, except that the V-shaped notch 93used in the FIG. 1 embodiment is replaced by a generally U-shapedcut-out or notch 93′ and that the mounting portions 92, 92′ are omitted(that is, those parts of the joint section extending above the uppersurfaces of the joint end portions 91, 91′ have been cut away) so thatthe entire joint section 90 may be press-fitted into a receptacle.Again, the depth D (see FIG. 2B) of the generally U-shaped notch 93′ ofthe joint section 90 from the top to the bottom thereof is so deep thatthe valley bottom of the notch 93′ is below the level defined by astraight line L extending between the lowest points of the sending sideand receiving side optically functional sections 81 and 82. As in thismodified form, even if the joint section 90 is configured to havelimited vertical dimensions over the entire length thereof, it may actas an optical guide. Consequently, there is a possibility that someamount of a sending side optical signal that has penetrated from thecolumnar sending side optically functional section 81 into the jointsection may propagate through the joint section to cause a considerablecross-talk (see FIG. 2A). Nevertheless, since the U-shaped notch 93′ isalso formed to have a sufficient depth from the top of the joint section90 that the valley bottom is located below the level defined by astraight line extending between the lowest points of the sending sideand receiving side optically functional sections 81 and 82, any lightwhich may have leaked from the sending side optically functionalsections 81 into the joint section will take an extended path of leakagebefore it reaches the receiving side optically functional section 82, sothat the leaked light will be attenuated during the process ofpropagating through the joint section 90 while diffusing, resulting in areduction in cross-talk (see FIG. 2B).

Next, a second embodiment of the invention will be described withreference to FIG. 3. In this embodiment, the vertical dimension M of thejoint section 90 is increased to enlarge the cross-sectional area, ascompared to the surface areas of the joint regions 91 a and 91 a′between the joint end portions 91 and 91′ and the columnar sending sideoptically functional section 81 and receiving side optically functionalsection 82, respectively, whereby any transmitted light that may havepenetrated into the joint section 90 will be diffused through theenlarged joint section so that the amount of the light which may enterthe receiving side optically functional section 82 will becorrespondingly decreased to thereby reduce cross-talk.

A modified form of the second embodiment of FIG. 3 will be describedwith reference to FIG. 4. This modified form is again configured toincrease the vertical dimension M (see FIG. 4B) of the joint section 90to thereby enlarge the cross-sectional area, as compared to the surfaceareas of the joint regions 91 a and 91 a′ between the joint end portions91 and 91′ and the sending side optically functional section 81 andreceiving side optically functional section 82, respectively.

Referring to FIG. 5, a further modified form of the second embodiment ofFIG. 3 will be described. In an optical coupling component 9 for use ina two-way optical communication connector comprising a pair of columnarsending side optically functional section 81 and columnar receiving sideoptically functional section 82, and a joint section 90 moldedintegrally with the optically functional sections made from the samematerial as the material from which the optically functional sectionsare made, this modified form is constructed to simply join the jointsection 90 with the side walls of the columnar sending side andreceiving side optically functional sections 81, 82 around thecircumferential length equal to or less than a half circumference of thecolumnar optically functional sections by means of the joint endportions 91, 91′. This modified form is again configured such that thejoint regions of the joint section are joined with the side walls of thecolumnar sending side and receiving side optically functional sections81, 82 around the circumferential length equal to or less than a halfcircumference of their columnar optically functional sections to therebyreduce the area of the joint region joining with the opticallyfunctional sections as compared to that of the earlier technique inwhich the joint section is joined with the optically functional sectionsaround their whole circumferences. Consequently, the amount of lightthat would otherwise have leaked through the joint section may bereduced to thereby produce the effect of enhancing the opticaltransmission efficiency.

A third embodiment of the invention will be described with reference toFIG. 6. In this embodiment as well, as in the embodiment of FIG. 1, theoptical coupling component 9 comprises a columnar sending side opticallyfunctional section 81, a columnar receiving side optically functionalsection 82, and a joint section 90 mechanically connecting the twooptically functional sections. In this embodiment, the joint section 90has U-shaped cut-outs or notches 93′ and 93″ both cut in the centerthereof from the top and bottom sides, respectively thereof, by means ofwhich the joint section may be fitted and fixed in a receptacle in sucha manner as to make the joint end portions of the joint section and thetwo optically functional sections free of (out of contact with) thereceptacle. It will be appreciated that in this embodiment as well, theamount of light that would otherwise have leaked through the jointsection may be reduced to enhance the optical transmission efficiencyand additionally that any light which may have leaked from the sendingside optically functional sections 81 into the joint section 90 willfollow an extended cross-talk path before it reaches the receiving sideoptically functional section 82, so that the leaked light will beattenuated during the process of propagating through the joint section90 while diffusing, resulting in a reduction in cross-talk.

A modified form of the third embodiment of FIG. 6 will be described withreference to FIG. 7. This modified form is similar to the embodiment ofFIG. 1, except that in place of the notch 93 in FIG. 1, an opening 930square in cut-out shape is formed in the center of the joint section 90.The joint section 90 is molded integrally with the columnar sending sideoptically functional section 81 and the columnar receiving sideoptically functional section 82 from the same material as the materialand made from the same material as that from which those opticallyfunctional sections are made, and it is fixed in a receptacle by meansof the square opening 930 formed through in its center.

A fourth embodiment will be described with reference to FIG. 9. This isan optical coupling component for use in an optical communicationconnector including a joint section 90 molded integrally with a columnarsending side optically functional section 81 and a columnar receivingside optically functional section 82 in which the joint section 90 isprovided with additional portions so formed as to leave a portion of theperimeter of the columnar cross-section of each of the opticallyfunctional sections exposed. As is apparent from the drawing, theoptical coupling component of this embodiment is configured such thatthe circumferential length (the arcuate length from the point A to thepoint B in FIG. 9B) of the joint regions 91 a, 91 a′ of the jointsection 90 circumferential of the side walls of the columnar opticallyfunctional sections where the joint section adjoins the outer peripheralsurfaces of the optically functional sections is equal to or less than ahalf circumference of the optically functional sections. Additionally,it should be understood that while this optical coupling component hassleeves 73, 74 added thereto as used in the earlier technique, theeffect of improving the optical transmission efficiency over the earliertechnique is not impaired since the circumferential length of the jointsurfaces is limited. Further, it should be noted that when constructingan optical connector using the optical coupling component of thisembodiment, the apertures 13 a, 13 b formed through the bottom wall 3should be large enough to pass these sleeves therethrough, asillustrated in the earlier technique.

INDUSTRIAL UTILITY

From the foregoing, it will be appreciated that the present inventionprovides an optical coupling component capable of improving the opticaltransmission efficiency and reducing cross-talk as compared to theearlier technique and an optical connector using such optical couplingcomponent, and can be put to effective use in the field of the two-wayoptical communication.

1. An optical coupling component for use in a two-way opticalcommunication connector comprising: a columnar sending side opticallyfunctional section and a columnar receiving side optically functionalsection in a pair, both made from optically transparent synthetic resinmaterial, and a joint section integrally molded with said opticallyfunctional sections and made from the same material as the material fromwhich said optically functional sections are made so that said pair ofsaid optically functional sections are mechanically joined to each otherinto one piece by means of said joint section, wherein: said jointsection has a body portion and opposite joint end portions, and each ofthe joint end portions has a joint region adjoining a circumferentialsurface of the corresponding columnar optically functional section, eachof the adjoining joint regions adjoins the corresponding columnaroptically functional section in a circumferential direction of thecorresponding columnar optically functional section for a length lessthan or equal to half the circumference of the corresponding columnaroptically functional section, and each of said joint regions of said endportions of said joint section has a vertical width H that is less thana vertical width M of said joint section.
 2. The optical couplingcomponent according to claim 1, wherein said body portion of said jointsection has a generally V-shaped or U-shaped notch in a central portionthereof with an apex lower than a level defined by a straight lineextending between the lower sides of said two optically functionalsections.
 3. The optical coupling component according to claim 1,wherein said body portion of said joint section has generally U-shapednotches in a central portion thereof cut in from the top and bottomedges thereof so that said body portion has a vertically narrowedcentral portion defined between facing bottoms of said notches.
 4. Theoptical coupling component according to claim 2 in an optical connector,the optical connector further comprising: a light-emitting element and alight-receiving element; and a connector body for housing therein saidlight-emitting and light-receiving elements and said optical couplingcomponent; wherein said columnar sending side and receiving sideoptically functional sections of said optical coupling component areadapted to establish optical coupling between said light emittingelement and said light receiving element on one hand and a sending sideoptical fiber and a receiving side optical fiber attached to an opticalplug on the other hand, respectively.
 5. The optical coupling componentaccording to claim 3 in an optical connector, the optical connectorfurther comprising: a light-emitting element and a light-receivingelement; and a connector body for housing therein said light-emittingand light-receiving elements and said optical coupling component;wherein said columnar sending side and receiving side opticallyfunctional sections of said optical coupling component are adapted toestablish optical coupling between said light emitting element and saidlight receiving element on one hand and a sending side optical fiber anda receiving side optical fiber attached to an optical plug on the otherhand, respectively.
 6. The optical coupling component according to claim2 in an optical connector, the optical connector further comprising: alight-emitting element and a light-receiving element; and a connectorbody including a wall which has a sending side optical fiberaccommodating tube in which a sending side optical fiber attached to anoptical plug is fitted, a receiving side optical fiber accommodatingtube in which a receiving side optical fiber attached to said opticalplug is fitted, a recess formed therein in which said optical couplingcomponent is fitted, and through-apertures formed therethrough extendingfrom said recess into communication wit said optical fiber accommodatingtubes; wherein said optical coupling component is inserted and fixed insaid recess while said optically functional sections are inserted insaid through-apertures in a manner such that one ends of said opticallyfunctional sections are positioned in opposition to said light-emittingelement and light-receiving element mounted in said connector body whilethe other ends of said optically functional sections are positionedwithin said through-apertures in opposition to said optical fibersfitted in said optical fiber accommodating tubes.
 7. The opticalcoupling component according to claim 3 in an optical connector, theoptical connector further comprising: a light-emitting element and alight-receiving element; and a connector body including a wall which hasa sending side optical fiber accommodating tube in which a sending sideoptical fiber attached to an optical plug is fitted, a receiving sideoptical fiber accommodating tube in which a receiving side optical fiberattached to said optical plug is fitted, a recess formed therein inwhich said optical coupling component is fitted, and through-aperturesformed therethrough extending from said recess into communication withsaid optical fiber accommodating tubes: wherein said optical couplingcomponent is inserted and fixed in said recess while said opticallyfunctional sections are inserted in said through-apertures in a mannersuch that one ends of said optically functional sections are positionedin opposition to said light-emitting element and light-receiving elementmounted in said connector body while the other ends of said opticallyfunctional sections are positioned within said through-apertures inopposition to said optical fibers fitted in said optical fiberaccommodating tubes.
 8. An optical connector comprising: alight-emitting element and a light-receiving element; the opticalcoupling component according to claim 1 2 3; and a connector body forhousing therein said light-emitting and light-receiving elements andsaid optical coupling component, wherein said columnar sending side andreceiving side optically functional sections of said optical couplingcomponent are adapted to establish optical coupling between said lightemitting element and said light receiving element on one hand and asending side optical fiber and a receiving side optical fiber attachedto an optical plug on the other hand, respectively.
 9. An opticalconnector comprising: a light-emitting element and a light-receivingelement; the optical coupling component according to claim 1, 2 or 3;and a connector body including a wall which has a sending side opticalfiber accommodating tube in which a sending side optical fiber attachedto an optical plug is fitted, a receiving side optical fiberaccommodating tube in which a receiving side optical fiber attached tosaid optical plug is fitted, a recess formed therein in which saidoptical coupling component is fitted, and through-apertures formedtherethrough extending from said recess into communication with saidoptical fiber accommodating tubes, wherein said optical couplingcomponent is inserted and fixed in said recess while said opticallyfunctional sections are inserted in said through-apertures in a mannersuch that one ends of said optically functional sections are positionedin opposition to said light-emitting element and light-receiving elementmounted in said connector body while the other ends of said opticallyfunctional sections are positioned within said through-apertures inopposition to said optical fibers fitted in said optical fiberaccommodating tubes.